Voicemail systems for use in storing and retrieving voicemail messages have been deployed for more than a decade. Today, voicemail messaging may be found in a unified messaging system (UMS) that handles voice, facsimile and regular text messages as objects in a single mailbox that a user can access either with a regular email client, or by telephone. A UMS typically connects to an IP-PBX to provide automated attendant, audiotext, and voice mail services to subscribers or users. For instance, a personal computer (PC) user with multimedia capabilities can open and playback voice messages, either as speech or text. Similarly, a person may retrieve their email messages as speech from a voice-over-IP (VoIP) phone connected through an IP network, or from a traditional telephone device connected with the enterprise via a conventional public switched telephone network (PSTN). Unified messaging is thus particularly convenient for mobile business users because it allows them to reach colleagues and customers through a PC or telephone device, whichever happens to be available.
Existing voicemail systems—whether implemented in a UMS or as a separate, stand-alone system—provide different functionalities such as the scheduling of a voice message, sending of the same voicemail to multiple people, saving of voicemail messages in a repository, etc. The content of the voicemail message, however, is static; i.e., its content does not change once the message has been left on the voicemail system. To put it differently, the entire content of the voicemail message in current voicemail systems is determined at the time the message is recorded. This means that if important conditions or information changes, a person may have to leave one (or multiple) new voicemail messages with the same recipient informing them of the new information and telling them to disregard the previous message.